diff options
| author | Frederic Weisbecker <frederic@kernel.org> | 2021-10-19 02:08:14 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-12 12:25:45 +0200 |
| commit | 40fb3812d99746f0322ada92fdc8d904a024e6de (patch) | |
| tree | 703b80dd0ba279622d4731aad0a8467505c0fd8f /kernel | |
| parent | 43dbc3edada66eaa9d406ea9647359e795288ea0 (diff) | |
rcu: Fix callbacks processing time limit retaining cond_resched()
commit 3e61e95e2d095e308616cba4ffb640f95a480e01 upstream.
The callbacks processing time limit makes sure we are not exceeding a
given amount of time executing the queue.
However its "continue" clause bypasses the cond_resched() call on
rcuc and NOCB kthreads, delaying it until we reach the limit, which can
be very long...
Make sure the scheduler has a higher priority than the time limit.
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
[UR: backport to 5.10-stable + commit update]
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcu/tree.c | 28 |
1 files changed, 16 insertions, 12 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 844c35803739..f340df6ebd86 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2490,10 +2490,22 @@ static void rcu_do_batch(struct rcu_data *rdp) * Stop only if limit reached and CPU has something to do. * Note: The rcl structure counts down from zero. */ - if (-rcl.len >= bl && !offloaded && - (need_resched() || - (!is_idle_task(current) && !rcu_is_callbacks_kthread()))) - break; + if (in_serving_softirq()) { + if (-rcl.len >= bl && (need_resched() || + (!is_idle_task(current) && !rcu_is_callbacks_kthread()))) + break; + } else { + local_bh_enable(); + lockdep_assert_irqs_enabled(); + cond_resched_tasks_rcu_qs(); + lockdep_assert_irqs_enabled(); + local_bh_disable(); + } + + /* + * Make sure we don't spend too much time here and deprive other + * softirq vectors of CPU cycles. + */ if (unlikely(tlimit)) { /* only call local_clock() every 32 callbacks */ if (likely((-rcl.len & 31) || local_clock() < tlimit)) @@ -2501,14 +2513,6 @@ static void rcu_do_batch(struct rcu_data *rdp) /* Exceeded the time limit, so leave. */ break; } - if (offloaded) { - WARN_ON_ONCE(in_serving_softirq()); - local_bh_enable(); - lockdep_assert_irqs_enabled(); - cond_resched_tasks_rcu_qs(); - lockdep_assert_irqs_enabled(); - local_bh_disable(); - } } local_irq_save(flags); |